unfasten

动词 unfasten:

1. cause to become undone
2. become undone or untied

1. He unfastened the buckles and took off the coat.
   他解开扣子，把上衣脱掉。
2. Now you can unfasten your seat belt.
   现在您可以解开安全带了。
3. Please unfasten your jacket and shirt and let me examine your heart and chest.
   请解开你上衣和衬衣的钮扣，我来听听你的心肺。